Metastasis of a transplantable mammary tumour in rats treated with cyclophosphamide and/or irradiation.

We report observations on the spread by metastasis and infiltration of a transplantable tumour in rats treated by 60Co gamma-irradiation of the primary, irradiation plus parenteral cyclophosphamide, or parenteral cyclophosphamide alone. The proportion of animals with overt disseminated disease and the extent of spread were measured with respect to the time elapsed after implantation and treatment of the primary tumour. The incidence of metastatic disease was broadly similar for all treatment groups, but the extent of dissemination was greater in rats whose treatment included cyclophosphamide.